Construction of roll for machinery



R. A. HESS Aug. 6, 1968 CONSTRUCTION OF ROLL FOR MACHINERY Filed April27, 1966 FIG.I

O Q I O l m w 2;

INVENTOR BYW wwmv afi ATTORNEY FIG.

United States 3,395,636 CONSTRUCTION OF ROLL FOR MACHINERY Ralph A.Hess, Medfield, Mass., assignor to SW Industries, Inc., Newton, Mass., acorporation of Massachusetts Filed Apr. 27, 1966, Ser. No. 545,597 8Claims. (Cl. 100-93) ABSTRACT OF THE DISCLOSURE The present inventionrelates to a novel roll construction of the type useful in a variety ofmachines, particularly paper making and processing machines, etc., and,more particularly, to a roll construction of the type having a metalliccore, the extremities of which are journaled, and an elastomericcovering or veneer, the physical and chemical properties of which areparticularly selected. The roll construction of the present invention isspecifically adapted for use in a calendering process wherein itrotatably presses against a rotatably mounted heated drum. The covering,which is relatively hard and thin is intended to compact the surface ofa paper or paperboard sheet that is advanced between the roll and thedrum for the purpose of providing gloss. In this process, it is desiredthat the roll covering maintain its predetermined hardness throughoutlong periods of time at elevated temperatures.

The primary object of the present invention is to provide a novel rollconstruction comprising a metallic core and a coverin incorporating, ina synthetic elastomeric matrix, a network of dispersed carbon particles,which have been found to conduct, to the roll core as a heat sink, heatgenerated within the covering as the roll continuously deforms duringrotation and heat transmitted to the covering from the drum or the like,toward which it is pressed. It has been found that a covering of theforegoing composition is capable of maintaining exceptionally constanthardness throughout a broad, high temperature range.

Other objects of the present invention will in part be obvious and willin part appear hereinafter.

For a fuller understanding of the nature and objects of the presentinvention, reference should be had to the following detailed disclosure,taken in connection with the accompanying drawing, wherein:

FIG. 1 is an exaggerated, cross-sectional view of a roll construction ofthe present invention;

FIG. 2 is an exaggerated cross-sectional View of a calendering station,for example, in a .paper making ma chine, embodying the presentinvention; and

FIG. 3 is a graph illustrating certain principles of the presentinvention.

Generally the roll construction embodying the present invention, asshown in FIG. 1, comprises as components: a cylindrical metallic core10, preferably composed of cast iron, bronze or steel; and a tubularcovering 12, preferably composed of an elastomeric external phase 14 anda carbon internal phase 16, in the form of a continuous network ofminute particles which are sufficiently closely adjacent to provide acontinuous path for the conduction of heat. In order to achieve suchheat conductive characteristics, the carbon is present in an amountranging from 20 to 80 parts based on 100 parts of elastomer and is inthe form of particles generally ranging in mean diameter between and 40millimicrons. Remaining comatent ponents of the covering includesuitable plasticizers, antioxidants and ifillers. As suggested in FIG.2, the roll structure of FIG. 1 is shown at 18 as the top roll of acalendering station having a heated drum 20. Typically, heated drum 20is maintained at a temperature, e.g., 300 to 400 F., higher than thetemperature of roll 18, which is grounded at alower temperature, e.g.,140 to 190 F. Roll 18 generally ranges from 14 to 30 inches in overalldiameter and its covering generally ranges from A to 1 inch inthickness. The overall length of drum 20 is similar to that of roll 18and its diameter generally ranges from 18 to 66 inches. Typically, thepressure between roll 18 and drum 20 ranges between 300 and 600 poundsper lineal inch. For best results, the hardness of covering 12 rangesfrom 3 to 20 P&] for a inch ball. (The use of the P&] hardness tester isdescribed in ASTM D53149).

The process of producing covering 12 generally comprises the step of (a)mixing the elastomeric matrix, which is in partially polymerized form,and the carbon particles, and blending therewith a plasticizing agent,an antioxidant and a filler, (b) adding an accelerator in order to timethe occurrence of vulcanization at some later specified time, (c)applying the blend to a metal core, and (d) heating from 5 to 35 hoursat a temperature from 250 to 350 F., the time range of 19 to 21 hoursand the temperature range of 260 to 270 F. being preferred. It is to berealized, of course, that cure is a function of both time andtemperature and, therefore, that cure may be varied widely within theforegoing limits.

Generally, the formulations discussed below are based upon 100 partselastomer, suitable elastomers being synthetic rubbers such aschloroprene, butadiene-styrene, butadiene-acrylonitrile,chlorosulfonated polyethylene, and ethylene-propylene terpolymer. Suchsynthetic elastomers, unlike natural elastomers, are not subjectgenerally to chain scission at elevated temperatures. Generally, asindicated below, the carbon content, which ranges from 20 to by weightof elastomer, is in the form of par ticles having a mean diameter offrom 10 to 40 millimicrons, being characterized by physical properties,by which network formation inherently occurs. Such a carbon is sold byColumbian Carbon Co. under the trade designation Conductex. This carbonnetwork contributes its inherent heat conducting characteristics to theelastomeric matrix in which it is dispersed without appreciablyaffecting adversely the desirable characteristics of the elastomericmatrix. This network has the ability to withstand deformation of theelastomeric matrix without any break in its continuity duringdeformation of the roll during use.

Generally, all of the below-mentioned additives are specified in termsof parts by weight based on parts by weight of elastomer. A plasticizingagent is present in the quantity from 0 to 50 parts, suitableplasticizing agents being coumaron indene resins, low molecular weighthydrocarbons such as glycol, and esters such as dioctyl phthalate.Generally an antioxidant is present in the quantity from 0 to 5 parts,suitable antioxidents being phenyl alpha naphthalene,N-phenyl-betal-naphthalene, alkylated phenol, isopropyl laminodiphenyland naphthalene. Generally a filler is present in the quantity from 0 to700 parts, suitable fillers being an inorganic material such as calciumcarbonate, silica, barium sulfate, hydrated aluminum silicate, magnesiumsilicate. Processed organic materials also may be used, includingvulcanized vegetable oil chlorinated vegetable oil. Generally anaccelerator is present in the quantity from .1 to 30 parts, suitaableaccelerators, including inorganic accelerators, such as lime and leadoxide and organic accelerators, such as peroxide,mercapto-benzothiozole, benzothiazyl disulfide, tetramethyl thiurammonosulfide, zinc dibenzyl dithiocarbamate, Zinc dibutyldithiocarbamate, butylaldehyde analine, diphenyl guanidine, diorthotolyguanidine.

3 Generally a vulcanizing agent is present, such as sulfur in thequantity of 0.1 to 45 parts or magnesium oxide in the quantity 1-20parts.

The following nonlimiting examples further illustrate the processes andproducts of the present invention.

EXAMPLE I First the following covering materials were thoroughly blendedby mixing for 75 minutes.

Parts by weight Elastomeric butadiene-styrene (70/30 weight The corewhich was composed of iron and. was 24 inches in diameter, was gritblasted and coated with a layer, 0.001 inch thick, of a cementincorporating neoprene in a ketonic solvent. Thereafter a cement havingthe following formulation was applied in a layer 0.001 inch thick: Partsby weight Neoprene 100.

Magnesia 4.

Phenyl alphanaphthalene 2.

Calcium silicate 10.

Zinc oxide 5.

Methyl ethyl ketone Sufficient quantity to disperse solids representingby total weight.

After drying the foregoing cement, the previously specified covering aswas applied onto the core in a layer /2 inch thick. Then, the veneer wascured at 260 F. for 20 hours. Finally, the outer surface Was smoothlyground. It was found that the roll of the foreging composition had thecurve of hardness vs. temperature shown at 22 in FIG. 3. Thecorresponding curve of the same composition without the conductivecarbon network is shown at 24 in FIG. 3.

EXAMPLE II The process of Example I was repeated except that the partsper weight of sulfur was doubled. The resulting covering was harder thanthe covering of Example I but exhibited a substantially constanthardness vs. temperature curve analagous to that of curve 22 in FIG. 3.

The present invention thus provides a calender roll exhibiting unusuallyconstant hardness throughout a very wide temperature range. Sincecertain changes may be made in the foregoing disclosure withoutdeparting from the scope of the invention disclosed herein, it isintended that all matter described in the foregoing description or shownin the accompanying drawings be interpreted in an illustrative and notin a limiting sense.

What is claimed is:

1. A calendering roll construction comprising a press roll and a heatedroll, said press roll including cylindrical inner core and a tubularouter covering, said inner core being composed of metal and having meansat its opposite extremities for mounting said roll construction forrotation, said tubular covering being composed of a syntheticelastomeric matrix and a dispersed network of heat conductive carbonparticles therein, the concentration of said carbon particles rangingbetween 20* to based on elastomer of said matrix and said particlessubstantially ranging in size between 10 and 40 millirnicrons, saidheated roll having a metallic surface.

2. The calendering roll construction of claim 1 wherein said heated rollis maintained at a temperature of 300 to 400 F.

3. The calendering roll construction of claim 1 wherein the pressurebetween said press roll and said heated roll is maintained at between300 to 600 pounds per lineal inch.

4. The calendering roll construction of claim 1 wherein said press rollvaries in temperature from 140 to 190 F.

5. The calendering roll construction of claim 1 wherein the hardness ofsaid covering ranges from 3 to 20 P81] for a inch ball.

6. The calendering roll construction of claim 1 wherein said coveringranges from /4 to 1 inch in thickness.

7. A roll construction comprising a press roll and a heated roll, saidpress roll including cylindrical inner core and a tubular outercovering, said inner core being composed of metal and having means atits opposite extremities for mounting said roll construction forrotation, said tubular covering being composed of a synthetic rubbermatrix and a dispersed network of heat conductive carbon particlestherein, the concentration of said carbon particles ranging between 25to based on elastomer of said matrix and said particles substantiallyranging in size between 10 and 40 millirnicrons, said heated roll havinga metallic surface, means for maintaining said heated roll at atemperature of 300 to 400 F., means for maintaining the pressure betweensaid press roll and said heated roll at a pressure of 300 to 600 poundsper lineal inch, means for maintaining the temperature of said pressroll from to F., the hardness of said covering ranging from 3 to 20 P&J.for inch ball, the cove-ring ranging from A to 1 inch in thickness.

8. A calendering roll construction comprising a press roll and a heatedroll, said press roll including cylindrical inner core and a tubularouter covering, said inner core being composed of a heat conductor andhaving means at its opposite extremities for mounting said rollconstruction for rotation, said tubular covering being composed of asynthetic elastomeric matrix and a dispersed network of heat conductivecarbon particles therein, the concentration of said carbon particlesranging bebetween 20 to 80% based on elastomer of said matrix and saidparticles substantially ranging in size between 10 and 40 millirnicrons,said heated roll having a heat conducting surface.

References Cited UNITED STATES PATENTS 2,373,876 4/1945 Cutler 29-1323,081,206 3/1963 Remer 29-132 X 3,092,895 6/1963 Balkin et a1. 29-1323,189,729 6/ 1965 Lusebrink.

LOUIS O. MAASSEL, Primary Examiner.

